class Solution {//leetcode1020——飞地的数量
private:
    int dx[4]={0,0,1,-1};
    int dy[4]={1,-1,0,0};
public:
    int numEnclaves(vector<vector<int>>& grid) {
        int m=grid.size(),n=grid[0].size();
        queue<pair<int,int>> q;
        for(int i=0;i<m;i++) {
            if(grid[i][0]==1) {
                q.push({i,0});
                grid[i][0]=2;
            }
            if(grid[i][n-1]==1) {
                q.push({i,n-1});
                grid[i][n-1]=2;
            }
        }
        for(int j=1;j<n-1;j++){
            if(grid[0][j]==1){
                q.push({0,j});
                grid[0][j]=2;
            }
            if(grid[m-1][j]==1){
                q.push({m-1,j});
                grid[m-1][j]=2;
            }
        }
        while(q.size()){
            auto [a,b]=q.front();
            for(int k=0;k<4;k++){
                int x=a+dx[k];
                int y=b+dy[k];
                if(x>=0&&x<m&&y>=0&&y<n&&grid[x][y]==1){
                    q.push({x,y});
                    grid[x][y]=2;
                }
            }
            q.pop();
        }
        int ret=0;
        for(int i=0;i<m;i++){
            for(int j=0;j<n;j++){
                if(grid[i][j]==1) ret++;
            }
        }
        return ret;
    }
};